The present invention relates to a machine tool that enables to accelerate a feed speed for three-dimensional direction of a spindle and to improve machining precision with the first and the second saddles.
A conventional machine tool has been already disclosed in a prior art reference, for example, the Japanese Patent Provisional Publication No. 365529 of 1992. As shown therein, the machine tool is defined by the column mounted fixedly onto a bed in the spindle direction, the first saddle guided on the column movably in vertical direction, the second saddle guided on the first saddle movably in lateral direction, and the spindle guided on the second saddle movably in the longitudinal direction.
The above first or second saddle is generally made of casting, and therefore the spindle head supported on these saddles sometimes vibrates to such an extent that affects machining precision in machining.
An object of this invention is to provide a machine tool that reasonably prevents vibrations of the spindle head and the like and enables a high-speed and a high-precision machining.
To achieve the above object, the invention is characterized by a machine tool having the following structure. That is, the machine tool comprises a bed, a column, a first saddle and a second saddle. The column forming a rectangular frame body making the central inside into a large space is mounted standingly onto one end of the bed so that the space is disposed on the front side. A pair of guide rails are mounted on the front surface of the column in vertical direction. On the other hand, the first saddle forming a square frame body whose upper and lower side members are made of prismatic members of rectangular cross-section, is movable to the vertical direction through the guide rails. A servomotor to drive laterally the following second saddle and a lateral screw axis combined with the servomotor are provided on the upper surface of the upper side member of the first saddle.
Besides, the second saddle is formed into a square frame body smaller in size than the first saddle and provided with a bulging member on the upper of the square frame body. The bulging member is screwed with the lateral screw axis so as to displace the second saddle in lateral direction. A pair of right and left square cylindrical members of rectangular cross-section are mounted on a lower rear surface of the square frame body in a specified length horizontal direction to cross at right angle to the rear surface. Besides, rail members are laid on the upper and lower prismatic bodies of the first saddle and the square cylindrical members of the second saddle. The invention is characterized by filling sealingly concrete into the prismatic bodies and a pair of right and left square cylindrical members provided with the guide rails.